The discovery of a vast number of biomarkers implicated in a wide variety of biological processes and the establishment of miniaturized microfluidic systems have opened up avenues to devise methods and systems for the prediction, diagnosis and treatment of diseases in a point-of-care setting. Point-of-care testing is particularly desirable because it rapidly delivers results to medical practitioners and enables faster consultation.
Performing assays, particularly immunoassays, on microfluidic systems of patient samples requires careful, precise calibration using data gathered in parallel with the sample measurement by measuring known standards or calibrators using the same assay protocol and reagents, or data provided by a manufacturer that are specific to a particular lot of reagents and assay conditions. Generally, such manufacturer provided calibration data are associated with strict temperature and other assay related conditions. Such calibration information is critical in accurately determining the relationship between the response or output from the assay system and the analyte concentration in a sample. Errors due to mis-calibration of distributed assay systems, especially in the case of immunoassays and particularly in the case of immunoassays that do not use “excess” reagents could lead to significant errors in determining the concentration of an analyte of interest.
There is therefore a significant need for methods that would improve the calibration in hand held or disposable assay units, particularly in those units where the sample and/or reagent volumes are in the microliter and nanoliter ranges, where maintaining a controlled temperature may be impractical, where the sample may not be “clean” such that errors are caused by interfering substances, or where it is difficult to maintain the desired conditions such as temperature, reagent quality, or sample volume.